<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>JS_修饰</title>

    <script>
        function $(id){return document.getElementById(id);}
        window.onload=function(){
        $("div1").style.width=200+"px";
        $("div1").style,height=200+"px";
        $("div1").style.border='150px solid red';
        $("div1").style.borderRadius='100px';
        $("div1").style.background='cyan';

        $("but").addE

        }
    </script>
    <style>
        .xian{display:block;}
        .xian{display:none;}
    </style>
</head>
<body>
<button id="but">display or not</button>
        <div id="div1"></div>

</body>
</html>